About Optics & Photonics TopicsOSA Publishing developed the Optics and Photonics Topics to help organize its diverse content more accurately by topic area. This topic browser contains over 2400 terms and is organized in a three-level hierarchy. Read more.

Topics can be refined further in the search results. The Topic facet will reveal the high-level topics associated with the articles returned in the search results.

Abstract

A numerical study has been carried out by means of the Green’s function method to explore possible performance improvements of a simple grated waveguide (GWg) by the variations of its grated structure. It is shown that a GWg featuring symmetric two-sided grated structure of 16 teeth with a 60nm groove depth and having a symmetric refractive index profile with a relatively large contrast between the grated and ungrated layers is capable of delivering largely improved device performance compared to that achieved previously with a one-sided grating of 40nm groove depth and asymmetric index profile. The improvement is characterized by a remarkable 8-fold and 15-fold increase in the group index and the maximum field intensity, respectively, at the first resonance wavelength above the upper band edge (shorter wavelength), while relatively less improvement is found at the first resonance wavelength below the lower band edge (longer wavelength). It is shown that more than 20% further improvement can be obtained by an appropriate shifting of the two innermost adjacent grating teeth in the case of the 40nm groove depth. Apart from that, the result also reveals an interesting and remarkable correlation between the variations of the group index and the confined energy.

References

You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Table 1

Calculated Operational Parameters of the Symmetric (gt=gb) Double-Sided GWg for Different Groove Depths at the Upper Resonance and Lower Resonance, Showing the Most Favorable Improvement Attained with a 60nm Groove Depth

Upper Resonance

gt, gb (nm)

λresu (nm)

T (dB)

R (dB)

L (dB/μm)

Ng

dNg/dλ (nm−1)

|Emax|2 (a.u.)

W (a.u.)

20

1074

∼0

−51.56

−23.06

3.970

0.031

4.68

12.17

40

1016

−0.002

−43.98

−10.05

6.501

0.275

14.14

15.57

60

917.6

−0.252

−36.99

−3.765

16.68

1.975

52.66

23.95

Lower Resonance

gt, gb (nm)

λresl (nm)

T (dB)

R (dB)

L (dB/μm)

Ng

dNg/dλ (nm−1)

|Emax|2 (a.u.)

W (a.u.)

20

1189

∼0

−44.06

−18.48

3.950

−0.024

4.29

12.10

40

1156

−0.001

−35.53

−14.15

6.693

−0.207

11.56

14.00

60

1124.6

−0.079

−36.58

−5.265

15.20

−1.225

33.26

15.79

Table 2

Further Variations of the Operational Parameters as the Results of Shifting the Two Adjacent Middle Teeth by Different Distances for the Upper and Lower Resonances

Upper Resonances

d (nm)

λresu (nm)

L (dB/μm)

Ng

dNg/dλ (nm−1)

|Emax|2 (a.u.)

W (a.u.)

0

1016

−10.05

6.501

0.275

14.14

15.57

70

1033

−5.223

8.173

0.200

28.11

18.66

−100

1023

−5.446

7.023

0.161

17.40

16.53

200

1011

−7.913

5.975

0.223

11.87

14.50

Lower Resonances

d (nm)

λresl (nm)

L (dB/μm)

Ng

dNg/dλ (nm−1)

|Emax|2 (a.u.)

W (a.u.)

0

1156

−14.15

6.693

−0.207

11.56

14.00

70

1141

−10.30

7.286

−0.199

14.40

15.60

−100

1125

−3.172

8.449

−0.226

23.03

17.85

200

1121

−2.949

8.625

−0.182

26.03

18.18

Tables (2)

Table 1

Calculated Operational Parameters of the Symmetric (gt=gb) Double-Sided GWg for Different Groove Depths at the Upper Resonance and Lower Resonance, Showing the Most Favorable Improvement Attained with a 60nm Groove Depth

Upper Resonance

gt, gb (nm)

λresu (nm)

T (dB)

R (dB)

L (dB/μm)

Ng

dNg/dλ (nm−1)

|Emax|2 (a.u.)

W (a.u.)

20

1074

∼0

−51.56

−23.06

3.970

0.031

4.68

12.17

40

1016

−0.002

−43.98

−10.05

6.501

0.275

14.14

15.57

60

917.6

−0.252

−36.99

−3.765

16.68

1.975

52.66

23.95

Lower Resonance

gt, gb (nm)

λresl (nm)

T (dB)

R (dB)

L (dB/μm)

Ng

dNg/dλ (nm−1)

|Emax|2 (a.u.)

W (a.u.)

20

1189

∼0

−44.06

−18.48

3.950

−0.024

4.29

12.10

40

1156

−0.001

−35.53

−14.15

6.693

−0.207

11.56

14.00

60

1124.6

−0.079

−36.58

−5.265

15.20

−1.225

33.26

15.79

Table 2

Further Variations of the Operational Parameters as the Results of Shifting the Two Adjacent Middle Teeth by Different Distances for the Upper and Lower Resonances